dt-bindings: wireless: wilc1000: Document WILC3000 compatible string

Document compatible string for the WILC3000 chip. The chip is similar
to WILC1000, except that the register layout is slightly different and
it does not support WPA3/SAE.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20241004114551.40236-1-marex@denx.de